Hydroxyalkylamine oxide detergent compounds



United States Patent 3,441,611 HY DROXYALKYLAMINE OXIDE DETERGENTCOMPOUNDS Howard F. Drew and Robert E. Hall, Wyoming, Ohio,

assignors to The Procter & Gamble Company, Cincinnati, Ohio, acorporation of Ohio No Drawing. Filed Dec. 4, 1961, Ser. No. 156,993Int. Cl. C07c 93/02 U.S. Cl. 260584 4 Claims ABSTRACT OF THE DISCLOSUREHydroxyalkylamine oxides have improved hygroscopicity and thermalstability properties and can be advantageously employed in detergentcompositions.

This invention relates to novel tertiary amine oxide detergents anddetergent compositions containing them.

In the constant improvement of organic detergent compounds, certainfeatures have been found to be highly desirable. These features includeresistance toward the ingredients imparting hardness to Water, a highdegree of detergency, and capacity for solubilization of hard watersoaps, such as calcium soap. Although there are a number of organicdetergents which have these characteristics, detergent compounds havingadditional desirable characteristics find a wider scope of application.

Thermal stability is a highly desirable property which is lacking inmany detergents. Such stability is particularly desirable whendetergents are subjected to heat during use or processing, as forexample, in spray drying granular detergent compositions.

Another advantageous property for an organic detergent is a low degreeof hygroscopicity which results in improved crystallinity. Whendetergent surfactants which are hygroscopic are used in bar or granularforms, desirable physical properties are impaired. Bars become soft andslimy and granules tend to cake and lose their free flowing and quickdissolving characteristics. For example, trialkylamine oxide have beenfound to be excellent detergent compounds but are so hygroscopic thatthey can be effectively used only in liquid detergent compositions.

It is the object of this invention to provide organic detergents anddetergent compositions which have excellent detergency characteristicsas well as improved mildness to the skin, improved thermal stability anda low degree of hygroscopicity.

It was found that these and other objects are achieved in a novel classof tertiary amine oxides having the structure set forth below anddetergent compositions containing such compounds, preferably in solidform, as hereinafter more fully described.

The amine oxides of this invention are:

In the above formulas R is a Z-hydroxyalkyl, 3-hydroxyalkyl or3alkoxy-2-hydroxypropyl radical in which the alkyl and alkoxy,respectively, range from to 18 carbon atoms in chain length, R; and Rare each methyl, ethyl, propyl or isopropyl. The class of compoundsdescribed above will hereinafter be referred to more simaS R1R2R3N9O.

Examples of the compounds of this invention are dimethyl 2hydroxydodecylamine oxide, diethyl-3-hydroxydodecylamine oxide,dimethyl-Z-hydroxytetradecylice amine oxide, dipropyl 3hydroxyhexadecylamine oxide, propylmethyl 2 hydroxyoctadecylamine oxide,diethyl- 2-hydroxyhexadecylamine oxide, diethyl-Z-hydroxytetradecylamineoxide, diisopropyl 2 hydroxydodecylamine oxide, N,Ndimethyl-3-dodecoxy-Z-hydroxypropylamine oxide, N,Ndiethyl-3-tetradecoxy-2-hydroxypropylamine oxide andmethylethyl-3-hydroxydodecylamine oxide.

Tertiary amine oxides as a broad class of compounds are known. It wassurprising to find, however, that the particular trialkylamine oxidescontaining particularlyplaced hydroxy groups as described above (i.e., ahydroxy group in the 2 or 3 position in R have such highly desirableproperties for use as organic detergents, i.e., improved mildness,hygroscopicity and thermal stability characteristics.

It appears that only certain tertiary amine oxides have theaforementioned desirable characteristics; in these certain amine oxides,R R and R must be as described above. If the alkyl or alkoxy in R islonger in chain length than 18 carbon atoms or shorter in chain lengththan 10 carbon atoms, desired detergency is not obtained. Likewise, if Rand R contain more than 3 carbon atoms, desired detergencycharacteristics are not obtained. The long chain R radical must containa hydroxy group in the 2 or 3 position (i.e., the second or third carbonatom from the nitrogen) in order to achieve improved mildness,hygroscopicity and thermo-stability characteristics in accordance withthis invention. When the hydroxy group in the R radical is in the l oralpha position, the resultant amine oxide compound has undesirableinstability. The 3-alkoxy-2-hydroxypropyl R radical has the followinggeneral formula:

wherein R ranges from 10 to 18 carbon atoms in chain length.

The 2-hydroxyalkyl, 3-hydroxyalkyl and the 3-alkoxy- 2-hydroxypropylcompounds have about the same reduced hygroscopicity characteristics ascompared to the corresponding compound containing unsubstituted R alkylgroup. The 3-hydroxyalkyl compound has about the same water solubilityas the corresponding compound containing an unsubstituted R alkyl groupwhereas the water solubility of the 2-hydroxyalkyl compound is somewhatless than the solubility of the corresponding compound containing anunsubstituted R group.

In tertiary amine oxides of this invention, R can be derived fromnaturally occurring fats and oils or from synthetic sources such asolefins. Mixtures of amine oxides are very suitable wherein the alkyl oralkoxy in R varies in chain length in the C to C range, as for example,the alkyl or alkoxy groups derived from coconut fatty alcohol (ordistilled coconut fatty alcohol). Those amine oxides in which the alkylor alkoxy in R ranges from 12 to 14 carbon atoms are preferred.

The tertiary amine oxides of this invention can be prepared, in general,by oxidizing the corresponding tertiary amine. See, for example, BritishPatent 437,566. The corresponding tertiary amine, in general, can beprepared by alkylating, with an appropriate long chain alkyl compound,the appropriate secondary amine. If necessary, the long chain alkylcompound can be such (e.g., ketoalkane) that treatment (e.g., reduction)of the tertiary amine, prior to oxidation, will result in hydroxysubstitution at the desired location in the R group. The examplesexplain in detail such reactions. The preparation of alkyl glycidylethers (a source of the 3-alkoxy-2-hyroxypropyl 3 R is described inCanadian Patent 582,404, issued September 1, 1959 and U.S. Patent2,989,547, issued June 20, 1961.

Compounds of this invention are useful per se as detergents and surfaceactive agents. Desirably they are used with other materials to formdetergent compositions, particularly solid form compositions as forexample, bar, flake, granular or tableted granular compositions. (Thetertiary amine oxides of this invention can also be used to make liquiddetergent compositions.) Such detergent compositions can contain fromabout 5% to about 80% of the tertiary amine oxides of this invention andfrom 95% to about 20% of anionic organic detergents, nonionic organicdetergents, water-soluble inorganic alkaline builder salts,water-soluble organic alkaline sequestrant builder salts or mixturesthereof.

Granular or flake detergents preferably contain about 5% to about 50% ofthe amine oxides of this invention and from about 95% to about 50%normally solid, water-soluble inorganic alkaline builder salts, orwatersoluble organic alkaline sequestrant builder salts. Barformulations contain about 5% to about 50% of the amine oxides of thisinvention when used with anionic detergents, such as a soap base, and,if desired, alkaline inorganic or organic builders or inert fillers. Barformulations can contain about 40% to about 80% of the amine oxides ofthis invention as the only detergent component, if desired, and thebalance inert fillers or builders.

Anionic organic detergents used alone or in admixture include both thesoap and non-soap detergents. Examples of suitable soaps are the sodium,potassium, ammonium and alkylol-ammonium salts of higher fatty acids (CC Particularly useful are the sodium and potassium salts of the mixturesof fatty acids derived from coconut oil and tallow, i.e., sodium orpotassium tallow and coconut soap. Examples of anionic organic non-soapdetergents are: alkyl glyceryl ether sulfonates; alkyl sulfates; alkylmonoglyceride sulfates or sulfonates; alkyl polyethenoxy ether sulfates;acyl sarcosinates; acyl esters of isethionates; acyl N-methyl taurides;alkyl-benezenesulfonates; alkyl phenol polyethenoxy sulfonates. In thesecompounds the alkyl and the acyl groups, respectively, contain 10 to 20carbon atoms. They are used in the form of water-soluble salts, thesodium, potassium, ammonium and alkylolammonium salts, for example.Specific examples are: sodium lauryl sulfate; potassium N- methyllauroyl tauride; triethanolammonium dodecylbenzenesulfonate.

The examples of nonionic organic detergents are: polyethylene oxidecondensates of alkyl phenols wherein the alkyl group contains from 6 to12 carbon atoms (e.g., 5- octylphenol) and the ethylene oxide is presentin a molar ratio of ethylene oxide to alkyl phenol in the range of 10:1to 25:1; condensation products of ethylene oxide with the productresulting from the reaction of propylene oxide and ethylene diaminewherein the molecular weight of the condensation products ranges from5,000 to 11,000; the condensation product of from about 5 to 30 moles ofethylene oxide with one mole of a straight or branched chain aliphaticalcohol containing from 8 to 18 carbon atoms (e. g., lauryl alcohol).

Water-soluble inorganic alkaline builder salts used alone or inadmixture are alkali metal carbonates, borates, phosphates,polyphosphates, bicarbonates and silicates. (Ammonium or substitutedammonium salts can also be used.) Specific examples of such salts aresodium tripolyphosphate, sodium carbonate, sodium tetraborate, sodiumpyrophosphate, sodium bicarbonate, potassium tripolyphosphate, potassiumpyrophosphate, sodium heXametaphosphate, sodium sesquicarbonate, sodiummonoand diortho phosphate and potassium bicarbonate. Such inorganicbuilder salts enhance the detergency of the subject amine oxides, 4

Examples of water-soluble organic alkaline sequestrant builder saltsused alone or in admixture are alkali metal, ammonium or substitutedammonium amino polycarboxylates, e.g., sodium and potassiumethylenediaminetetraacetate, sodium and potassium N-(2-hydroxyethyl)-ethylenediaminetriacetates, sodium and potassium nitrilotriacetates andsodium, potassium, and triethanolammoniumN-(Z-hydroxyethyl)nitrilodiacetates. Mixed salts of thesepolycarboxylates are also suitable. Other organic alkaline sequestrantbuilder salts which can be used are:Hydroxyethylethylenediaminetriacetates; 2 hydroxyethyliminodiacetates;diethylenetriamine pentaacetates; 1,2- diaminocyclohexanetetraacetates.The alkali metal salts of phytic acid, e.g., sodium phytate are alsosuitable as alkaline organic sequestrant builder salts (see U.S. Patent2,739,942).

Preferred detergent compositions contain about 10% to about 30% of thetertiary amine oxides of the invention and at least an equal amount ofsodium tripolyphosphate. Desirably the amine oxides wherein the alkyl oralkoxy in R contains 12 to 14 carbon atoms are used in such preferredcompositions. Particularly desirable is dimethyl-2- hydroxydodecylamineoxide which has good sudsing characteristics, being superior in thisrespect to dimethyldodecylamine oxide. It also is an effective sudsenhancing (building) agent for anionic non-soap detergent compounds.

The detergent compositions of this invention can contain any of theusual adjuvants, diluents or additives, for example, ampholytic orzwitterionic detergents, cationic detergents, perfumes, anti-tarnishingagents, anti-redeposition agents, bacteriostatic agents, dyes,fluorescers, oxygen or chlorine bleaches, suds builders, suds depressorsand the like.

The following are examples which illustrate the tertiary amine oxidecompounds and compositions of this invention.

Example I 5 moles of dimethyl amine were liquified under anhydrousconditions using a Dry Ice-acetone condenser. 0.05 mole of anhydrousaluminum chloride was added to the dimethyl amine and a mixture wasplaced in a cold, glass autoclave liner (3 liter). One mole of C olefinoxide was added to the dimethylamine with mixing and cooling. The linerwas placed in a cooled autoclave. After sealing the autoclave, themixture was heated at 200 C. for three hours. The autogeuic pressure was300 to 400 p.s.i.g. After cooling the autoclave and flushing it with Nthe contents were dissolved in aqueous solution of 10% HCl to hydrolyzethe resulting amine-aluminum chloride complex. The solution was madebasic with solid KOH and the upper amine layer was removed for vacuumdistillation. A 70% yield of distilled dimethyl-2-hydroxydodecylaminewas obtained. Elemental analysis of the resulting amine was as follows:

Calculated: C, 73.3; H, 13.6; N, 6.1; O, 7.0. Found: C, 73.4; H, 13.3;N, 5.8; O, 7.2.

The reaction is represented by the following equation:

oxidation reaction and subsequent purification was 95%.

A mixture of dimethyl-2-hydroxyhexadecyl amine oxide anddimethyl-Z-hydroxyoctadecyl amine oxide was obtained from the aboveprocess using instead of the C olefin oxide a 60-40 mixture of C olefinoxide.

The corresponding diethyl and dipropyl compounds can be obtained byusing molar equivalent amounts of diethylamine or dipropylamine in theprocess of Example I.

20 parts of dimethyl-2-hydroxydodecyl amine oxide are combined with 50parts of sodium tripolyphosphate and 30 parts of sodium sulfate to forma solid form detergent composition which cleans well in a launderingoperation and suds well in a dishwashing operation. The dishpan sudsingof dimethyl-Z-hydroxydodecyl amine oxide in such a composition issuperior to that of sodium dodecylbenzene sulfonate in a likecomposition.

Example II 170 grams of 2-undecanone, 22.5 grams of paraformaldehyde,40.8 grams of dimethyl amine hydrochloride were mixed with 500 ml. ofethanol and stirred for 24 hours at 78 C. The reaction mixture wasacidified and extracted with ethyl ether to remove the unreacted 2-undecanone. The mixture was then made alkaline and extracted again withethyl ether to obtain 81 grams of 3-ketododecyl dimethyl amine.

The reaction is represented by the following equation:

38 grams of LiAlH, was dissolved in 600 ml. of anhydrous diethylether.57 grams of the 3-keto dodecyl dimethyl amine obtained above wasdissolved in 400 ml. of diethylether and added drop-wise to the LiAlH,solution. This mixture was then stirred for an additional 1 /2 hours.The unreacted LiAlH, was decomposed by the addition of ethyl acetatefollowed by Water. The solution was filtered to remove solids. Thefiltrate split into aqueous and ether layers. The ether layer wasevaporated on a steam bath to yield the hydroxy amine. This reaction isrepresented by the following equation:

Calculated: Amine number, 244; hydroxyl number, 244. Found: Aminenumber, 240; hydroxyl number, 277.

45 grams of the dimethyl-3-hydroxydodecyl amine obtained above, wasmixed with 8.5 grams of hydrogen peroxide (28.5 grams of a 30% aqueoussolution) and 250 ml. of ethanol and 125 ml. of water. This mixture wasstirred for 6 hours at 50 C. After cooling to room temperature thesolution was diluted with 400 m1. of water and the remaining peroxidedecomposed catalytically. The unreacted amine was removed with a tripleether extraction. The ethanol was largely removed from solution on asteam bath and the product was isolated by freeze drying. The amineoxide was recrystallized from acetone and had the following elementalanalysisCalculated: Percent C, 68.50; percent H, 12.73; percent N, 5.71.Found: Percent C, 67.89; percent H, 12.40; percent N, 5.67.

The resulting dimethyl-3-hydroxydodecyl amine oxide was tested forhygroscopicity, being compared with the Z-hydroxydodecyldimethyl amineoxide of Example I and with an unsubstituted dimethyldodecyl amineoxide. The hygroscopicity was determined by exposing dry recrystallizedmaterial in a constant 50% relative humidity chamber at 70 F.

It is apparent that the 3-hydroxydodecyl and the 2-hydroxydodecylcompounds are markedly less hygroscopic than the unsubstituted dodecylcompound. The thermal stability of the compounds of this invention areindicated by decomposition temperatures of the 3-hydroxydodecyl and the2-hydroxydodecyl compounds of 145 C. and 130 C. respectively as comparedto C. decomposition temperature of unsubstituted dimethyldodecyl amineoxide.

The dimethyl 3-hydroxydodecyl amine oxide and thedimethyl-Z-hydroxydodecyl amine oxide were tested for detergencyproperties. These amine oxides were substantially equivalent indetergency to sodium dodecylbenzenesulfonate. The determination was madeby washing naturally soiled cloth (desized print cloth) swatches in an0.1% aqueous solution of a mixture of 20% of an organic detergentcompound (amine oxide being tested or alkylbenzenesulfonate standard)50% sodium tripolyphosphate and 30% sodium sulfate. The composition hada pH of 10 and the Washing was done at F. for 10 minutes using washwater of 7 grains per gallon hardness. The detergency effectiveness wasdetermined by measuring the percentage of lipid soil remaining on astandard size swatch (on a dry basis) after the washing operation. Thepercentage of lipid soil remaining after washing with the amine oxidetest composition was compared with the percentage after washing with thealkyl'benzenesulfonate standard composition. On the basis of the percentresidual lipid soil, the lower the percent, the better the detergencyperformance. A Ter-gotometer was used for the washing Operation.(Tergotometer testing is described in Detergency Evaluation and Testingby J. C. Harris, Interscience Publishers, Inc. (1954), page 60.)

Diethyl-2-hydroxytetradecylamine oxide, diisopropyl-3-hydroxyphexadecylamine oxide and dimethyl-2-hydroxyalkylamine oxidewherein the alkyl is derived from coconut fatty alcohol can be made byprocesses similar to those described in Examples I and II. Thesecompounds will have substantially equivalent thermal stability andhygroscopicity characteristics and the detergency efiicacy will beslightly less than that of the hydroxydodecyl compounds.

Example III 1,818 grams of dodecyl glycidyl ether was charged into a twoliter autoclave. Air was purged from the head space with dimethyl amine.The autoclave was then heated to 390 F. A pressure of 450 p.s.i. wasobtained in the autoclave by charging dimethyl amine into the autoclaveusing nitrogen pressure. A dimethyl amine bleed valve was adjustedduring the reaction of the ether with the dimethyl amine to keep aconstant pressure and temperature. After one hour, the autoclave wascooled. The resultant N,N-dimethyl-3-dodecoxy-2-hydroxypropylaminecontained about 25% dissolved dimethylamine which was stripped off at175 F. at mm. Hg pressure. The amination reaction is represented by thefollowing equation:

1000 grams of this tertiary amine was mixed with 2789.3 grams of water,heated to 180 F. and mixed with 462 10 grams of 25% aqueous solution ofhydrogen peroxide. The mixture was vigorously agitated. The resultantmixture was aged overnight at about 170 F. to decompose excess peroxide.

The resultant N,N dimethyl 3 dodecoxy-Z-hydroxypropylamine oxideabsorbed only 0.3% water after one week of storage in an open vessel atroom temperature and conditions. Only 22% water was absorbed uponextreme storage conditions of 90 F. and 80% relative humidity for 7days. This amine oxide exhibited excellent detergency and sudsingcharacteristics and has excellent thermal stability.

N,N diethyl 3 tetradecoxy-2-hydroxypropylamine oxide andN,N-dimethyl-3-hexadecoxy-Z-hydroxypropylamine oxide can be prepared byprocesses similar to that 25 described in Example II. These compoundshave improved characteristics similar to those of the dodecyl compound.

The tertiary amine oxides of this invention can be used in effectivedetergent compositions having improved hygroscopicity and thermalstability characteristics. They have the following formulas:

Granular detergent: Percent Dimethyl-2-hydroxydodecyl amine oxide 17.5Sodium sulfate 23 Sodium tripolyphosphate 50 Sodium silicate 6 Water 3.5

Granular detergent:

Diethyl-Z-hydroxydodecyl amine oxide l0 Sodium dodecylbenzenesulfonate(the dodecyl group being derived from tetrapropylene) 10 Sodiumnitrilotriacetate 35 Sodium sulfate 40 Water 5 Granular detergent:

Dipropyl-3-hydroxy tetradecyl amine oxide 10 Condensation product of onemole of nonylphenol and nine moles of ethylene oxide 10 Sodiumpyrophosphate 50 Sodium carbonate 3 Trisodium phosphate 3 Sodium sulfate24 Granular detergent: Parts Dimethyl-Z-hydroxydodecylamine oxide 1Potassium ethylenediaminetetraacetate 2 Granular detergent:

Dimethyl-3-hydroxydodecylamine oxide 1 Potassium pyrophosphate 5Spray-dried granular detergent: Percent N,N dimethyl 3dodecoxy-Z-hydroxypropyl amine oxide 5 Sodium dodeeylbenzenesulfonate 15Sodium tripolyphosphate 50 Sodium sulfate 15 Sodium silicate 5 Moisture10 7 Milled toilet bar:

Diethyl-3-hydroxytetradecylamine oxide Ma ma 10 Sodium coconut oil soap15 Sodium tallow soap 60 8 Milled toilet bar: Percent Triethanolammoniumethylenediaminetetraace- To show the improvement in mildness of thecompounds of this invention over trialkylamine oxides Without a hydroxygroup in the long chain R radical, dimethyldodecylamine oxide anddimethyl-2-hydroxy-dodecylamine oxide were tested in accordance with theguinea pig immersion test. This test consists of immersing guinea pigshaving shaved undersides up to their thorax in a 02% solution of thematerial being tested at 37 C. for a 4 /2 hour period per day for threeconsecutive days. The animals are graded three days after the lastimmersion. The grades are the average of the results on not less thanthree animals. A 1 to 10 scale is used to rate the effects of theprolonged exposure of the test solution on the :animals skin. Grade 10represents ideal or perfect skin (soft, smooth and flexible) and theeffect of a theoretically perfectly mild detergent compound; grade 1represents severely irritated skin. Other values represent graduationsof severity between these extremes. Grade 1 in the guinea pig immersiontest indicates severely thickened, dry, cracked and bleeding skin, i.e.,extreme irritation. (Grade 1 in exaggerated tests on human subjectswould indicate severe redness and dryness of the skin. Exaggeratedexposure tests on guinea pigs are much more extreme than those conductedon human subjects.) There is a good correlation between the results ofthe tests on guinea pigs and the results of normal use tests on humans;the guinea pig immersion test can be relied on to grade the relativemildness of detergent compounds toward the human skin. In guinea pigimmersion tests dimethyldodecylamine oxide had a grade of 2, whiledimethyl-Z-hydroxydodecylamine oxide had a grade of 5.

What is claimed is:

1. Tertiary amine oxides having the formula wherein R is3-alkoxy-2-hydroxypropyl, in which the alkoxy ranges in chain lengthfrom 10 to 18 carbon atoms, and R and R are each selected from the groupconsisting of methyl, ethyl, propyl and isopropyl.

2. N,N-dirnethyl-3-alkoxy-2-hydroxypropyl amine oxide wherein the alkoxyranges in chain length from 10 to 18 carbon atoms.

N,N dimethyl 3-dodecoxy-Z-hydroxypropylamine 0x1 e.

4. N,N dimethyl 3-tetradecoxy-Z-hydroxypropylamine oxide.

References Cited UNITED STATES PATENTS 1,993,542 3/1935 Caspe 2605832,060,568 11/1936 Graenacher et al. 260-583 2,999,068 9/1961 Pilcher eta1 252-137 3,001,945 9/1961 Drew et a1. 252152 3,047,579 7/1962 Whitman260583 XR 2,169,976 8/ 1939 Guenther et a1. 260-404.5

CHARLES B. PARKER, Primary Examiner. ANTON H. SUTTO, Assistant Examiner.

US. Cl. X.R.

